Stockholders' Equity (Tables)

9 Months Ended

Sep. 30, 2020

Equity [Abstract]

Summary of Stock Based Compensation Expense

Stock-based compensation expense was recognized in the condensed consolidated statements of operations as follows (in thousands).

	Three Months Ended September 30,				Nine Months Ended September 30,
	2020		2019		2020		2019
Research and development	$	91	$	42	$	252	$	132
General and administrative		283		111		855		489
Total	$	374	$	153	$	1,107	$	621

Schedule of Fair Value of Award Granted Using Black-Scholes Option Pricing Model

The fair value of each award was estimated on the date of grant using the Black-Scholes option pricing model with the following assumptions

	Three Months Ended	Nine Months Ended September 30,
	September 30, 2020	2020	2019
Expected life (years)	6.0	5.5-6.0	5.5-6.1
Risk-free interest rate	0.4%	0.4%-0.5%	1.9%-2.6%
Volatility	84%	64%-84%	70%-71%
Dividend rate	—  %	—  %	—  %

Summary of Stock Option Transactions

The following table summarizes stock option transactions for the nine months ended September 30, 2020 as issued under the 2014 Plan:

	Number of Options			Weighted- Average Exercise Price per		Weighted Average Remaining Contractual Term
	Outstanding			Share		(in years)
Balance at January 1, 2020		2,123,117		$	4.62		7.87
Options granted		500,150		$	3.26
Options exercised		(8,518	)	$	1.96
Options canceled/forfeited		(101,010	)	$	2.34
Balance at September 30, 2020		2,513,739		$	4.45		7.58
Options vested at September 30, 2020		1,447,808		$	5.95		6.76
Options vested and expected to vest at September 30, 2020		2,513,739		$	4.45		7.58

Summary of Restricted Stock Unit Transactions

The following table summarizes restricted stock unit transactions for the nine months ended September 30, 2020 as issued under the 2014 Plan:

	Number of Restricted Stock Units			Weighted- Average Grant-Date Fair Value per Share
Outstanding at January 1, 2020		—
Restricted stock units granted		727,065		$	3.74
Restricted stock units vested		(78,565	)	$	2.87
Restricted stock units cancelled		(67,500	)	$	3.85
Outstanding at September 30, 2020		581,000		$	3.85